Financial support: EPIMAD is organized under an agreement between the Institut National de la Santé et de la Recherche Médicale (INSERM) and the Institut National de Veille Sanitaire (InVS) and also received a financial support of the François Aupetit Association, Lion's Club of Northwestern France, Ferring Laboratories, the Société Nationale Française de Gastroentérologie, Lille University Hospital and GIS-Maladies Rares (INSERM 2003). Potential competing interests: none.